Laboratory Studies of Electric Current Generated during Fracture of Coal and Rock in Rock Burst Coal Mine

Abstract

Experiments show that electric current would be produced in uniaxial compression of coal and roof rock. The electric current of coal shows a rapid increasing tendency when the loading stress is greater than or equal to 0.75σmaxwhich can be regarded as an omen for coal failure. The current of roof rock shows reversal tendency while loading stress is greater than or equal to 0.91σmaxand revised from negative to positive at the main fracture and the reversal of current can be regarded as the omen of rock fracture. There are obvious differences in physical and mechanical properties, composition, and failure process between coal and rock. The dominant mechanism of electric current generated by coal is triboelectrification of coal particles and charge separation during crack propagation. The mechanism of electric current of roof rock is piezoelectric effect of quartz materials in the early stage and charge separation during crack propagation in the later stage of loading. It can be found that the rapid increasing and reversal characteristic of electric current can reflect the failure process of coal and roof rock, respectively. Thus, it can be considered the omen of coal and rock failure.

Notched marble plates under tension: Detecting prefailure indicators and predicting entrance to the “critical stage”

“…Moreover, the form of the PSC can be used to distinguish whether plasticity (nonreversible deformation of the specimen) has appeared or whether fracture is impending . The technique is adopted by many researchers worldwide, while techniques based on quite similar concepts were recently introduced …”

“…Moreover, the form of the PSC can be used to distinguish whether plasticity (nonreversible deformation of the specimen) has appeared or whether fracture is impending. 16,31 The technique is adopted by many researchers worldwide, [26][27][28][29][30][31][32] while techniques based on quite similar concepts were recently introduced. 33 A basic characteristic of the PSCs detected during axial compression is that for loads within the elastic regime, a very weak variation of the electric current is recorded.…”

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“…As an extension of Latent Dirichlet Allocation (LDA), which is the best received topic-modeling technique, Steyvers et al [14] proposed the author-topic modeling technique that analyzes authors and topics simultaneously. They identify the authors’ impact or productivity of researchers in a given subject area [15, 16]. By adding multiple conditions to LDA, Tang et al [17] suggested a new methodology, called the Author-Conference-Topic (ACT) model that analyzes the author, conference, and topic in one model to understand the subject area in an integrated manner.…”